iPhone 3gs not activating after restore from jailbreak

Hi,

My friend has 2 old 3g's (i think they are both 3gs) but the guy he is selling them too asked if they could be resored without the jailbeak on them.

As he doesnt have a pc I offered to restore them for him. After plugging them in, updating them and restoring them neither of them will get past the activation stage.

It comes up on itunes as '

We are unable to continue with your activation at this time.

Please try again later, or contact customer care.

Any help would be greatly appreciated.